I would add some white on whites to use as neutrals and to help stretch the fabric so you have enough. You could also add some solids if needed to set of the patterns in the dresses. Since you are doing 4 quilts you might want to keep the patterns simple. Evening star alternated with 9 patches in a chain or other blocks that are not too complicated can still give a pretty effect. Also setting blocks on point can make the quilt larger with fewer blocks to piece.